Lubricant



Patented Jan. 10, 1939 UNITED STATES v LUBRICANT Melvin A. Dietrich, Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware N Drawing. Application June 23, 1937, Serial No. 149,883

9 Claims.

This invention relates to lubricants, and particularly to lubricants providing thin film lubrication and to stabilized lubricating oils.

Many agents have been proposed for use in lubricating oils for producing lubricants which will provide thin film lubrication. Some of these agents are organic phosphates, esters of organic acids, chlorinated compounds, sulfur compounds and the like. Most of such agents aid in reducing the friction. Also many of such agents tend to increase the tendency of the oils to form sludge. Further, various amines and phenols have been added to lubricating oils to retard the formation of sludge, but such sludge inhibiting agents do not, in general, provide thin film lubrication.

It is desirable, in some types of apparatus, to employ a friction drive comprising a driven member and a driving member which have only surface contact with each other. The driving member is forced strongly against the driven member, and the friction between the two surfaces is sufficient to cause the driven member to move with the driving member. In such apparatus, the two surfaces in contact tend to seize and the surfaces become scarred and have particles of metal torn bodily out of them. These disadvantages have greatly retarded the commercial use of such apparatus. It is also desirable to lubricate such members when their surfaces are not in operative contact. However, one cannot employ a lubricant which would decrease the coefiicient of friction between the surfaces, when in operative engagement, to such an extent as to prevent operation of the apparatus. An ordinary lubricating oil, providing only thick film lubrication, is satisfactory for lubricating the surfaces of the members, when out of operative contact, and will permit metal to metal contact for operating purposes. However, such a lubricating oil does not prevent the wearing, scuffing and seizing of the bearing surfaces. On the other hand, many of the well known thin film lubricants will prevent the wearing, scuffing and seizing but, due to their low coefiicient of friction, they will fail to provide sufficient friction for the apparatus to be operative.

It is an object of the present invention to provide materials for addition to lubricating oils, which materials will aid in providing thin film lubrication and tend to retard sludge formation. A further object is to provide materials to be added to lubricating oils which will render the oils particularly adapted for lubricating friction drive apparatus or, in other words, lubricants which are adapted to transmit applied energy.

A still further object is to provide lubricants which are more stable and which are useful in transmitting applied energy. A further object is to provide a method of lubrication, particularly on bearing surfaces under high pressure and for friction driven apparatus. Other objects are to provide new compositions of matter and to advance the art. Still other objects will appear hereinafter.

The' above objects may be accomplished in accordance with my invention which comprises incorporating in lubricating oils and greases, and particularly in oils and greases derived from petroleum, a small amount of anacetal, containing at least one free hydroxyl group, obtainable by the reaction of a polyhydric alcohol with an aldehyde containing at least 6 carbon atoms. I preferably employ neutral acetals and particularly those consisting of carbon, hydrogen and oxygen which may be obtained from the simple unsubstituted polyhydric alcohols such as glycerin, sorbitol and the like, although non-acidic polyhydric alcohols containing aldehyde, ketone or amino groups or halogen substituents may be employed for producing acetals suitable for use in accordance with my invention. I also prefer to employ the acetals prepared from a mixture of aldehydes, such as those obtained by the oxidation of mixtures of alcohols containing an average of 6 or more carbon atoms, and particu-- larly from alcohols which are obtained through high pressure synthesis from carbon oxides and hydrogen.

The acetals of my invention have the advantage over other materials employed for similar purposes in that they are generally liquids and are easily soluble in mineral oils. They can be incorporated in the lubricating oil or grease by mixing with the oil or grease and heating with stirring until solution is complete. The concentration of acetal employed will generally be from about 1 to about 5% by weight of the oil, and the temperature required for solution is generally below 100 0. Amounts up to may be employed to produce oils and greases having the desired property of providing thin film lubrication. When used in oils employed as lubricants for equipment transmitting applied energy, that is for frictional power transmission, quantities as high as 50% may be employed, if desired.

The method of testing my compounds to determine the property of providing thin film lubrication was that devised by J. 0. Allmen (Oil 8; Gas Journal, 30, 109, 1931). This method consists of running a 4" diameter drill rod between two halves of a split bushing which is maintained stationary. The load on the bushing is controllable. A hydraulic system for increasing the loading on the bushing until the oil film breaks and the metal seizes is provided. The rubbing speed is about 50 ft. per minute and the method of loading is gradual, one weight being added to the loading lever each 10 seconds. Each weight added to the loading lever increases the pressure on the bushing by about 125 pounds. The machine provides for beam loadings up to 20 weights, which corresponds to a pressure of 20,000 pounds per sq. in. on the full projected area of the drill rod. The resulting values roughly represent the film strength or film resistance.

In order more clearly to illustrate my invention, the preferred modes of carrying the same into effect and the advantageous results to be obtained thereby, the following examples are given:

Eatample I A mixture of acetals was prepared by the reaction of glycerin with the mixed aldehydes obtained by oxidation of alcohols having a boiling range of 150-160 C. and obtained by high pressure synthesis from carbon oxides and hydrogen. 1% of this mixture of acetals was added with stirring and mild heating to an S. A. E. 30 petroleum oil. The treated oil withstood a load of 6,000 lbs. per sq. in., whereas the original oil, without the acetal, withstood only 2,000 lbs. per sq. in.

Example II A mixture of acetals was prepared from glycerin and the mixed aldehydes obtained from alcohols having a boiling range of 200-225 C. and obtained by high pressure synthesis from carbon oxides and hydrogen. One per cent of this acetal was added to an S. A. E. 30 petroleum oil with stirring and mild heating. This treated oil carried a load of 6,000 lbs. per sq. in., whereas the original oil carried only 2,000 lbs. per sq. in.

The treated lubricants of the preceding examples had a high coefiicient of friction under pressures of over 2,000 lbs. per sq. in., that is, in thin film form. Accordingly, these lubricants were particularly adapted for use in friction drive apparatus, that is, in transmitting applied energy.

Other acetals may be prepared from aldehydes other than those disclosed in the examples. Some of such other aldehydes are dodecyl aldehyde, 2- ethyl-hexanal, 2-ethyl-hexenal, cyclic aldehydes and naturally occurring aldehydes. Mixed hydroxylated acetals derived from a mixture of aldehydes are also suitable for use in accordance with my invention. Similar compounds derived from aliphatic ketones may also be suitable.

other acetals may be derived from other polymethyl glucamine, and from polyhydric halides represented by sorbitol chlorhydrin. In the case of the polyhydric amines such as glucamine, the first reaction product may be an oxazole which, by reaction on the remaining hydroxyls, will form the hydroxylated acetal.

By incorporating the acetals in lubricating oils and greases, such oils and greases are given the characteristic of providing thin film lubrication.

The acetals do. not increase the acidity or corrosive action of the oil and do not deleteriously any substantial thickening of the oil.

Neither do the acetals cause While I have disclosed the addition of the acetals to the oils, they may be incorporated in the oils by first adding the alcohol and the aldehyde to the oil and causing them to react in the oil to produce the desired product in solution in the oil.

While I have disclosed the preferred embodiments of my invention and the preferred mode of carrying the same into efiect, it will be readily apparent to those skilled in the art that many variations and modifications may be made therein without departing from the spirit of my invention. Accordingly, the scope of my invention is to be limited solely by the appended claims construed as broadly as is permissible in view of the prior art.

I claim:

1. Lubricants comprising lubricating oils having incorporated therein liydro xylated acetals ing incorporated therein hydroxylated acetals obtainable by the reaction of polyhydric alcohols with aliphatic aldehydes containing at least six carbon atoms.

3. Lubricants comprising lubricating oils having incorporated therein a mixture of hydroxylated acetals obtainable by the reaction of polyhydric alcohols with a mixture of aliphatic aldehydes containing at least six carbon atoms.

4. Lubricants comprising lubricating oils having incorporated therein a mixture of hydroxylated acetals obtainable by the reaction of polyhydric alcohols with a mixture of aliphatic aldehydes prepared by oxidation of a mixture of alcohols boiling between about to about 225 C., which alcohols have been synthesized from carbon oxides and hydrogen.

5. Lubricants comprising lubricating oils having incorporated therein hydroxylated acetals obtainable by the reaction of glycerin with members selected from the class of aliphatic aldehydes and aliphatic ketones containing at least six carbon atoms.

6. Lubricants comprising lubricating oils having incorporated therein a mixture of hydroxylated acetals obtainable by the reaction of glycerine with a mixture of aliphatic aldehydes containing at least six carbon atoms.

7. Lubricants comprising lubricating oils having incorporated therein a mixture of hydroxylated acetals obtainable by the reaction of glycerin with a mixture of aliphatic aldehydes prepared by oxidation of a mixture of alcohols boiling between about 150 to about 225 C., which alcohols have been synthesized from carbon oxides and hydro.- gen.

8. A lubricant comprising a lubricating oil having incorporated therein a hydroxylated acetal obtainable by the reaction of glycerin with 2- ethyl-hexenal.

9. A lubricant comprising a lubricating oil having incorporated therein 9, hy droxylated ace tal obtainable by the reaction" of glycerin with dodecyl aldehyde.

MELVIN A. DIETRICH.

CERTIFICATE OF CORRECTION. Patent No. 2,1L ,1L 2. January 10, 19 9.

MELVIN A. DIETRICH. It is hereby certified that error appears hethe printed specification of the above nwnberedpmquiring c column, line 28, for "acetal" read mixture of acetals; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 21st day of February, A. D. 1959.

Henry Van Arsdale.

(Seal) Acting Commissioner of Patents.

rection as follows: Page 2, fi rst ff 

